江苏盐城上冈全新世颗石藻及其环境控制
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摘要
盐城上冈地区全新世期间处于泥砂质潮滩环境。根据有孔虫组合分析 ,这套近岸潮滩沉积代表潮下带 -潮间带 -潮上带的一次大海退过程。本文分析了上冈村砖瓦厂采泥坑东侧 SGE柱状剖面全新统的颗石藻化石 ,结果发现这套沉积物仅仅含 Gephyrocapsa oceanica单一属种 ,而且丰度较低。但这个种在剖面上的丰度分布显示三分性 :即自下至上为贫乏或缺失间隔、较常见间隔和常见间隔 ,基本上对应于潮下带、潮间带和潮上带。一般情况下 ,潮坪区由海向陆水动力由强至弱 ,各相带的水动力条件不同 ,其沉积特征各异。颗石藻胳架十分细微 ,在海水中往往以悬浮形式搬运 ,并在水动力较弱时停积。所以 ,水动力是 G.oceanica分布的直接控制因素
According to the analyses of foraminifera assemblages, Shanggang area was situated in the tidal flat and was under the process of regression from subtidal zone to supratidal zone throughout Holocene. The SGE column section with a total of 420cm in length located about 100m in the east of Shanggang village mainly consists of muds, silts and fine sands. The results of 48 samples studied for calcareous nannofossils from this column show that Gephyrocapsa oceanica Kamptner (1943) is a unique species and very low in abundance. On the basis of the abundance variation of G.oceanica this section can be subdivided into three divisions from bottom to top. Division 1 The interval is 0—140cm. G. oceanica rarely occurred in some samples and completely missed in most samples. The sediments possessing ripple lamination, parallel lamination and cross stratification include fine sands, medium fine silts, as well as muds, which were formed under the environment of the subtidal zone with higher energy. Division 2 There is an interval from 140cm to 332cm, where G.oceanica is common except sandy samples. The sediments are composed of sand and mud and increased in mud content toward upper part. The sedimentary structures mainly in clude lenticular stratification and interlayered stratification. This division, therefore, suggests environments from the lower flat to upper flat with a decrease in the energy of seawater. Division 3 This interval is the 322—420cm interval with an increase of large quantities of mud content. G.oceanica here is more common than that of division 2, which may be related with the decrease in the water energy under the conditions of a high flat supratidal zone. To sum up, it seems that the distribution pattern of G.oceanica in tidal flat area is directly controlled by hydraulics of seawater.
According to the analyses of foraminifera assemblages, Shanggang area was situated in the tidal flat and was under the process of regression from subtidal zone to supratidal zone throughout Holocene. The SGE column section with a total of 420cm in length located about 100m in the east of Shanggang village mainly consists of muds, silts and fine sands. The results of 48 samples studied for calcareous nannofossils from this column show that Gephyrocapsa oceanica Kamptner (1943) is a unique species and very low in abundance. On the basis of the abundance variation of G.oceanica this section can be subdivided into three divisions from bottom to top. Division 1 The interval is 0—140cm. G. oceanica rarely occurred in some samples and completely missed in most samples. The sediments possessing ripple lamination, parallel lamination and cross stratification include fine sands, medium fine silts, as well as muds, which were formed under the environment of the subtidal zone with higher energy. Division 2 There is an interval from 140cm to 332cm, where G.oceanica is common except sandy samples. The sediments are composed of sand and mud and increased in mud content toward upper part. The sedimentary structures mainly in clude lenticular stratification and interlayered stratification. This division, therefore, suggests environments from the lower flat to upper flat with a decrease in the energy of seawater. Division 3 This interval is the 322—420cm interval with an increase of large quantities of mud content. G.oceanica here is more common than that of division 2, which may be related with the decrease in the water energy under the conditions of a high flat supratidal zone. To sum up, it seems that the distribution pattern of G.oceanica in tidal flat area is directly controlled by hydraulics of seawater.
引文
王 建 ,徐永辉 ,孙爱梅 ,汪永进 ,1999.江苏中部潮汐层理所记录的环境信息研究 .第四纪研究 ,6期 ,5 70
张茂恒 ,王 建 ,1999.盐城上岗全新世有孔虫组合的环境意义 .中国地理学会地貌与第四纪专业委员会编《地貌 .环境 .发展—1999年嶂石岩会议文集》,182— 186页 ,中国环境科学出版社
任美锷 ,张忍顺 ,杨巨海 ,章大初 ,1983 .风暴潮对淤泥质海岸的影响 .海洋地质与第四纪地质 ,3 ( 4 ) :1— 15
张国栋 ,王益友 ,朱静昌 ,董荣鑫 ,吴 萍 ,1984.苏北港现代潮坪沉积 .沉积学报 ,2 ( 2 ) :3 7— 5 1
钟石兰 ,刘金陵 ,吴顺根 ,周山富 ,William Y.B. Chang,1996.江苏海门王浩钻孔全新世钙质超微化石的环境意义 .古生物学报 ,3 5( 2 ) :187— 198
Okada H,1992 .ogeographic control of modern nannofossil asemblage in surface sediments of Ise Bay,Mikawa Bay and ku-m ano-Nada,off coast of central Japan. Memorie di Science Ge-ologiche,43 :43 1— 449
张茂恒 ,王 建 ,1999.盐城上岗全新世有孔虫组合的环境意义 .中国地理学会地貌与第四纪专业委员会编《地貌 .环境 .发展—1999年嶂石岩会议文集》,182— 186页 ,中国环境科学出版社
任美锷 ,张忍顺 ,杨巨海 ,章大初 ,1983 .风暴潮对淤泥质海岸的影响 .海洋地质与第四纪地质 ,3 ( 4 ) :1— 15
张国栋 ,王益友 ,朱静昌 ,董荣鑫 ,吴 萍 ,1984.苏北港现代潮坪沉积 .沉积学报 ,2 ( 2 ) :3 7— 5 1
钟石兰 ,刘金陵 ,吴顺根 ,周山富 ,William Y.B. Chang,1996.江苏海门王浩钻孔全新世钙质超微化石的环境意义 .古生物学报 ,3 5( 2 ) :187— 198
Okada H,1992 .ogeographic control of modern nannofossil asemblage in surface sediments of Ise Bay,Mikawa Bay and ku-m ano-Nada,off coast of central Japan. Memorie di Science Ge-ologiche,43 :43 1— 449
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